Re: [Groff] condition: OR of two string comparisons

[Carsten Kunze]

> No.  Only the part where this register is set gets interpreted with
> the new syntax.

You're right.  This is a good solution.

> Note that groff doesn't convert macros into an internal
> representation; they are only stored and interpreted on demand (this
> has both advantages and disadvantages).  Thus the need for `.de1' and
> friends.

Ah, I did get you wrong here, I had read .de1 as .de 1 in old two character ID 
mode...

> Assuming we make register `.C' writable, it could be
> 
>   .nr \(.C 2
>   ... modern syntax
>   .nr \(.C 1
>   ... compatibility mode
>   .nr \(.C 0
>   ... normal groff syntax

Good solution...
(I think you mean .nr .C 2 etc.?)

> > (Anyway that new register does not hurt if it is additional.  But it
> > may have advantages to decide per request which expression syntax is
> > used.)
> 
> Mhmm.  Not sure whether this is a good idea.

Agreed, and not needed with e.g. setting of .C.

> We already have a mechanism for executing groff extensions in
> compatibility mode, so I think it would be reasonable to have the same
> for handling the new expression mode.

Yes, of course.

Carsten